rails habtm relation

Question

I have 2 models which have a has_and_belongs_to_many relation:

class Category < ActiveRecord::Base
  has_and_belongs_to_many :templates
end

class Template < ActiveRecord::Base
  has_and_belongs_to_many :categories
end

I want to know how can I get a category name through this relation, for example I find a first template:

t = Template.find(:first)

Then using t.categories will return an object, but I want to have category.name in return, how can I achieve this?

Is a template supposed to have one category or many categories in your domain? — MattMcKnight, Dec 22 '09 at 14:40

score 3 · Accepted Answer · answered Dec 22 '09 at 14:27

3

To get the names of the categories associated with your first Template instance, you can do:

Template.first.categories.collect(&:name)

—This uses the Symbol#to_proc support that Rails adds. More information in this Railscast.

answered Dec 22 '09 at 14:27

John Topley

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can i create a link for each of these items in this way ? how can i put some space between each item ? thnx for your help :) – datisdesign Dec 22 '09 at 15:50

score 0 · Answer 2 · answered Dec 22 '09 at 14:25

0

t.categories.first.name

answered Dec 22 '09 at 14:25

Jordan Running

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That only gets you the name of the first category associated with the template. I believe the OP wants the name of all the categories. – John Topley Dec 22 '09 at 14:29
1

But he says "I want to get a category name" not category names. I think he may not be understanding the many part of habtm. – MattMcKnight Dec 22 '09 at 14:39

score 0 · Answer 3 · answered Dec 22 '09 at 14:26

0

Supposing that a category record has the name field you can do:

t.categories.map(&:name)

answered Dec 22 '09 at 14:26

khelll

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whats the different between map and collect methods ? – datisdesign Dec 22 '09 at 15:10
they are the same, name aliases only. – khelll Dec 22 '09 at 15:22

rails habtm relation

3 Answers3